1. Field of the Invention
The present invention relates to a process for preparing 2-aminoethyl esters of methacrylic acid (hereinafter referred to as 2-AEMA) by the reaction of methacrylic acid with an aziridine compound.
2. Discussion of Related Art
The 2-AEMA compounds produced by the present invention are useful compounds as raw material for dispersants, flocculants, coagulants, paper additives used for a retention aid, drainage aid, strength aid, thickening agent, adhesive, chelate resin, ion-exchange resin, resin for enhanced oil recovery, photo-resist material, enzyme carrier, antibacterial resin, and modifier and processing aid used for the manufacture of fibers, plastics, paints, inks, papers and other products.
For the preparation of 2-AEMA, for example, a process disclosed in U.S. Pat. No. 3336358 is conventionally known. According to this process, first, methacrylic acid (hereinafter referred to as MA) is brought to react with an aziridine compound (hereinafter referred to as Az) in a saturated (or an unsaturated) aliphatic hydrocarbon solvent. Next, an inorganic acid is added to the prepared 2-AEMA, and an inorganic salt of 2-AEMA is separated.
A process disclosed in U.S. Pat. No. 4500728 is known as a method which achieves improved yields of the desired product compared to the above process. In this process, 2-isopropenyl-2-oxazoline (hereinafter referred to as IPO) is added to an aqueous solution containing a specified acid, so that 2-AEMA of high purity is produced.
However, the process of U.S. Pat. No. 3336358 yields a low selectivity of the desired product, i.e. 2-AEMA, while forming large amounts of by-products. In addition, as 2-AEMA has a double bond, some parts of the 2-AEMA are converted to a polymer when the inorganic acid is added.
Meanwhile, the process of U.S. Pat. No. 4500728 requires a number of procedures for preparing the IPO, i.e. the raw material. Therefore, considering the yield of the 2-AEMA from the starting materials used for the preparation of IPO, the yield is extremely low due to the large number of procedures, thereby resulting in high manufacturing costs.